System of control fob feinting



Jan. 9, 1940. E. H. LAABS 2,186,113

SYSTEM OF CONTROL FOR PRINTING PRESSES AND OTHER MACHINERY Filed Feb. 9,1939 2 sheets-sheet 1 Jan. 9, 1940. E, H, A s 2,186,113

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Patented Jan. 9, 1940 UNITED STATES SYSTEM or common ron rnnvrmo massesAND OTHER. momma! Eric H. Laabs, Milwaukee, Wis., calm to Cutler-Hammer,Inc., Milwaukee, Win, a corporation of Delaware Application February 9,

20 Claims.

This invention relates to systems of control for printing presses andother machinery.

Newspaper presses commonly have been provided with all electric drivescomprising a small 8 motor for starting, inching and threading speed anda large motor for printing speeds. Such drives have proven verysuccessful for printing presses and other machines. On the other hand, amore recently developed hydraulic drive comprising an electricallydriven hydraulic generator supplying a hydraulic motor has been used forprinting press drive with some degree of success, the single hydraulicmotor being used for starting, inching and running. However, the onlyoutstanding operating advantage of the hydraulic motor drive over thetwo-motor electric drive lies in the intermediate speeds obtainable withthe former, certain of the commonly employed types of electric motorspresenting difliculties in Q obtaining the desired intermediate speeds.As against this advantage the hydraulic motor drive has numerousdisadvantages, especially when used in connection with printing presses.As is well known, the starting torque of such a press is very muchgreater than its running torque, and thus the hydraulic motor to besuccessful must be much larger than it need be for driving the press atspeed. Again there is a delay involved in starting the hydraulic motor,and this is undesir- 30 able particularly in inching where it should bepossible to gauge the motion of the press from the length of time theinching button is held depressed, beginning the calculation at themoment the button is depressed. Furthermore, the 35 period ofpreparation of the press during which only inching and threadingoperations are required may run into hours, and where the hydraulicmotor drive is used for inching and threading the motor operating thehydraulic generator must be always in operation to avoid further delaysin starting, and this involves a great waste of electrical energy.

The present invention has among its objects 45 to provide a systemenabling use of the hydraulic type of drive free from the aforementionedand other disadvantages. v

Another object is to provide a system which in part is hydraulic and inpart electric to obtain the aforementioned and other advantages of bothhereinbefore discussed types of drives.

Another object is to provide such a composite system which will affordcontrol of the press or other driven machine in substantially the samemanner as that afforded by an all electric system.

1939, Serial No. 255,555

Other objects and advantages of the invention will hereinafter appear.

Oneembodiment of the invention is illustrated in the accompanyingdrawings which will now be described, it being understood that theembodi- 6 ment selected for illustration is susceptible of variousmodifications without departing from the scope of the appended claims.

' In the drawings,

Figure 1 is a schematic view showing the driven and driving elements ofthe system.

Fig. 2 shows power connections for the electric motor driving thehydraulic generator employed.

Fig. 3 shows the power circuits for a separate electric motor which isemployed.

Fig. 4 shows the power connections for the electric pilot motor of thehydraulic generator unit.

Fig. 5 shows the control instrumentalities and the control circuits inan across-the-line form, and

Fig. 6 is a chart showing the windings and contacts of the variousswitches or relays of Fig. 5 coordinated by vertical alignment andaligned horizontally with Fig. 5 to indicate their respec- 2s tivepositions therein.

Referring to Fig. 1, there is schematically shown a press I having adrive shaft 2 to which is connected an electric motor I and a hydraulicmotor 4. In practice the motor I preferably is connected to the shaft 2by a V-belt or silent chain 5, although any other suitable connectionsmight be employed. It is contemplated to employ the hydraulic motor 4only for printing speeds and to utilize the electric motor 3 for astarting, inching and threading. Thus it may be assumed that the motor 3is of the type and size usually employed for starting, inching andthreading, said motor preferably being connected to shaft 3 through anover-running clutch 6, pro- 40 vided for freeing the shaft 2 from theelectric motor drive when the hydraulic motor takes over the drive. Theoverrunning clutch 6 could of course be replaced by a suitablycontrolled electromagnetic clutch. As shown the overrunning a clutch 8is mounted on shaft 2 and may be connected to motor 3 by gearing asshown or by a V-belt or by a silent chain.

For supplying the hydraulic motor there is shown schematically acommercial form of unit comprising hydraulic generator ll driven by anelectric motor H and suitably piped to the hydraulic motor through avalve I! having an operating solenoid I l. The piping also includes arelief valve ll. This unit provides for regulation 3 having a suitablyoperated limit switch l6.

of the speed of the motor 4 through regulation at the generator' it,this regulation being accomplished through the medium of a pilot motorl6 As will be understood, the limit switch I6 stops the pilotwmotor whenthe generator regulator has been driven to either of two extreme limits.In addition to the contacts required for such limits the limit switch i6is provided with contacts hereinafter set forth to be operated inintermediate positions of said switch. Also as will be understood, thevalve I2 is to be operated by its solenoid whenever the press is set inmotion. The system illustrated being as aforestated of a well known typeand its specific form being immaterial to the present invention furtherdescription thereof appears needless. 7

Referring to Fig. 2, the motor ll employed to drive the hydraulicgenerator is shown as of the three phase alternating current typeconnected to supply lines L L, L through a suitable panel whichpreferably includes an overload device comprising contacts ill and atrip winding 22. This trip winding 22 is shown as connected in serieswith its contacts 2| across supply lines L --L through a double poleknife switch 23, a normally closed stop switch 24 and normally closedcontacts 26' of a relay 26. Thus opening of the "stop" switch 24 orrelay 26 will have the same effect as response of the overload, and aswill be understood operation of any one of these instrumentalities wouldbe utilized in one of the well known ways to effect disconnection ofmotor Ii. A relay 26 has its winding connected across the leads fromlines L and L said relay having normally open contacts 26' and serving apurpose hereinafter explained. The relay 23, as will be apparent, isenergized to close its contacts 26 while motor I I is running and torelease said cTontacts when said motor is disconnected from circuit.

Referring to Fig. 3, the starting and inching motor 3 is shown ascomprising a 3 phase alternating current motor supplied from lines L, U,L hrough a triple pole knife switch 33, fuses 3| and an electromagneticmain switch 32 having normally open contacts in each phase of thecircuit. Two phases of the motor circuit include overload windings 33.Assuming the knife switch to be closed the motor 3 may be started andstopped for inching the press by energizing and deenergizing theelectromagnetic main switch 32.

Referring to Fig. 4, the pilot motor l6 for the hydraulic generator isshown ascomprising a 3 phase alternating current motor supplied fromlines L L and L through fuses 36, a triple pole knife switch 34 and on"and o electromagnetic switches 36 and 31, respectively. Each of switches36 and 31 is of the triple pole type having normally open contacts ineach of the three phases of the motor circuit, and these switches havedifferent line connections whereby they afford operation of the motor l6in reverse directions, selectively. As will be understood, when it isdesired to operate the pilot motor for increasing the speed of thehydraulic motor the on switch is energized until the desired speed hasbeen obtained, whereupon it is deenergized, the speed change beinggoverned by the duration of the pilot motor. On the other hand, when itis desired to decrease the speed of the hydraulic motor the o switch isenergized to effect operation of the pilot motor in a reverse directionuntil the desired speed change has been effected whereupon the oflswitch is to be deenergized.

Two phases of the pilot motor circuit are preferably provided withoverload coils 46 and II, respectively, and preferably the pilot motoris provided with an electrically controlled brake 42 shown asconnected-to all three phases of the motor circuit.

Further referring to Fig. 4, the same also shows the power connectionsfor the solenoid l3 of the valve l2. More specifically it shows thissolenoid connected across lines L and L through normally open contacts63 of an electroresponsive relay 63.

Referring now to Fig. 6, the same shows at the bottom thereof thewinding of relay 26 of Fig. 2, and near the middle the winding of switch32 of Fig. 3. Also at the top of this figure are shown the windings ofelectromagnetic on and fofl' switches 36 and 31 of Fig. 4, and belowthese the winding of relay 63 of Fig. 4. The windings 36 and 31 have incircuit therewith contacts 46 and ll to be actuated by the overloadcoils l3 and 4| of Fig.4.

The additional relays shown in Fig. 6 will best be understood by firstreferring to Fig. 6. These relays include an of! relay 60 havingnormally open contacts 6i] and normally closed contacts 60' and an onrelay 6| having normally open contacts 6|, 6i and 6l. These relayscontrol the windings of the "off and on switches 36 and 31,respectively. The relays also include a stop relay 52 having normallyclosed contacts 62 and normally open contacts 62 62 and 62, an inch"relay 63 having normally open contacts 63*, 63 and 63 and normallyclosed contacts 63, a safe after inch" relay 64 having normally opencontacts 64 and 64 and normally closed contacts 64, a run relay 66having normally open contacts 66*, 66 and 66, a reset relay 66 havingnormally open contacts 66* and a safe relay 61 having normally closedcontacts 6''. Relay 63 is here shown as having normally open contacts 66and normally closed contacts 68', whereas as shown in Fig. 4 itadditionally has normally open contacts 63. A relay 69 havingnormally-open contacts 63* and a relay 60 having normally open contacts66* and 6|) are also included.

Fig. 5 additionally shows an of! push button switch 6|, a stop pushbutton switch 62, an inch push button switch 63, an on push buttonswitch 64, a "preset push button switch 66, a reset push button switch66, a safe-run push button switch 61 and an emergency stop push buttonswitch 63.

Fig. 5 additionally shows contacts l6 and Il of limit switch I6 (Fig. 1)to be opened in extreme positions respectively of said limit switch, l6being the on limit contacts in circuit with relay windings 6| and 63,and i6 being the of! limit contacts in circuit with relay windings 63and 69. Also it shows contacts l6 of said limit switch connected incircuit with relay winding 32, said contacts being arranged to be openedshortly after the pilot motor i6, Fig. 1, starts the limit switch I 6away from of! position. Further Fig. 5 shows contacts l6 of limit switchi6 connected in circuit with relay winding 6|, these contacts beingarranged for opening slightly in advance of contacts 16 and to beshort-circuited by contacts 26 of relay 26 (Fig. 2) upon energization ofsaid relay. The contacts 33'' shown in circuit with relay winding 62 areadapted to be operated by either of the overload windings 33 (Fig. 3).

The control is such that before the press or other driven machine may bestarted by pressing either the "inc or the on buttons the reset" pushbutton switch 55 must first be depressed. when push button switch 55 isdepressed the winding of relay 55 is connected across lines L L throughsaid push button switch and normally closed contacts 51 of relay 51.Relay 55 thereupon responds to connect through its contacts 55' thewinding of relay 52, across lines L and 11. through the overload switch33 and resistance r. Relay 52 then responds and through its contacts 52establishes a maintaining circuit for itself and through its contacts 52establishes a connection between line L and certain of therelaywindings. Furthermore relay 52 in responding completes through itscontacts 52' a maintaining circuit for the winding of relay 55, saidmaintaining circuit including normally closed contacts 54 of relay 54and shuntingpuslr button switch 55.

N With relays 52 and 55 energized the usually employed signal systemwould indicate and depression of the inch push button switch 53 then iseffective for inching. Depression of this push button switch connectsthe winding of inch" relay 53 across lines L, L through the normallyclosed contacts 51' of relay 51, subject to disconnection upon releaseof said push button switch.

Relay 53 in responding establishes a connection from line L throughitscontacts 53 to and through the winding of the starting switch 32 of theinching motor, to and through limit switch IS to and through the nowclosed contacts 52 to line L Switch 32 thus responds. to start the smallmotor 3 for inching subject to termination of the inching operation byrelease of the push button switch 53 to deenergize the inching relay 53which in turn deenergizes the switch 32.

. In themeantime during the inching operation the solenoid operatedvalve i2, Fig. l, is energized. The inching relay 53 upon respondingacts through its contacts 53 to establish a connection from line L toand through the winding of relay 58 to and through the now closedcontacts 52 to line L This relay completes the circuit of the solenoidl3 shown in Fig. 4. When the inch push button is released then the relay58 is deenergized through deenergization of the inching relay-todisconnect the valve solenoid from circuit.

During the inching operation the relay 55 also is energized and thiseffects restoration of circuits following release of the inc push buttonswitch, such as to necessitate repeating of the reset cycle firstdescribed above prior to a further inching operation or to startingthrough operation of the "on button. The energizing circuit of relay 54is completed by contacts 53 of the inch relay and relay 54 in respondingestablishes through its contacts 54 a maintaining circuit shunting thecontacts 53. Also relay 54 in responding closes its contacts 54connected in a shunt around the winding of. relay 52. This shuntincludes a resistance r, and normally closed contacts 53 and'58 ofrelays 53 and 55. Thus when relays 53 and 55 are deenergized followingrelease of the inch" push button switch the relay 52is deenergized byshunting of its winding, and releases to disengage its contacts 52restoring the circuits to the condition shown.

Assuming repetition of the resetting cycle followed by depression of theon" push button switch instead of the inch push button switch the "onrelay 5| is energized. The circuit of the on" relay may be traced fromline L through on" push buton switch 54 and normally closed contacts55'' of the ofP' relay to and through winding II to andthrough limitswitches l5 and II in series to and through normally closed contacts 51'of relay 5! to line L. The on" relay remains energized only so long asthe on" push button switch is held depressed. The on" relay 5| uponresponding connects in parallel with its 55 and 5| complete theenergizing circuit of the on" switch 35 of Fig.4. This, assuming thatthe hydraulic generator 'is in operation, provides for starting andaccelerating the hydraulic motor to take over the press drive, thedegree of accelera- I tion being determined by the length of time the onpush button is held depressed. As will be understood, when the on pushbutton is released the pilot motor |5 controlling the hydraulicgenerator is arrested for continued operation of the press at theselected speed until stopping or a speed change is directed. A furtherincrease in speed may of course be obtained by again depressing the onpush button switch 54. If, on the other hand, a speed reduction isdesired, then the "oflP push button switch Si is depressed to connectacross lines L and L the winding of off" relay 50. Off relay inresponding acts through its contacts 50* to energize the oif switch 31.of Fig. 4 to operate the pilot motor in a reverse direction subject toarrest when the off push button switch is released.

If when the on relay 5| is energized to start the pilot motor awayfromoff limit the hydraulic system is not in operation then shortly thelimit switch contacts I5 open to deenergize on relay 5| to stop thepilot motor. The slow speed drive continues and when the hydraulicsystem is started relay 25 responds to short-circuit limit switchcontacts ii for reenergization of the on. relay when the on push buttonswitch is closed. When the drive is taken over by the hydraulic motorthe limit switch contacts l5 open to deenergize relay 32 fordisconnection of the electric starting motor 3.

With the press in operation as the result of depression of the on pushbutton switch stopping may be effected by depressing the stop pushbutton switch 52. The push button switch 62 when depressed alone shuntsthe winding of stop relay 52 through resistance r causing.

deenergization of said stop" relay with consequent restoration ofcircuit connections, such as to necessitate repetition of. the firstdescribed reset cycle before the press can be restarted.

Stopping automatically is provided for by a paper break switch 10 whichwhen closing while the press is in operation establishes a shunt for thewinding of stop" switch 52 which extends through said paper breakswitch, the normally closed contacts 53 of the inch relay and the--contacts 54 of relay 54 which is closed during running operation.

- Throughout the time that oilP' limit switch I6 is closed the windingof relay 59 is connected across lines L and L and this relay inresponding parallels through its contacts 59 the circuit includingcontacts 53' and 54 of relays 53 and 55, respectively. Thus prior torestarting while the paper break switch is closed the pilot motor mustbe operated to of! position to open contacts It for deenergization ofrelay I9, thereby confining operation to a threading speed until thepaper break is repaired to restore the paper break switch to openposition.

In some instances it is desirable to bring the press to a preset speedby momentary depression of a push button, and this can be accomplishedby so depressing push button switch 65. This establishes circuit fromline L to and through the winding of relay 80, to andthrough the limitswitch IE", to and through contacts 51 of relay 51 to line L Relay 60upon responding completes through its contacts 60 a maintaining circuitfor itself and through said contacts and contacts 60' in series acircuit for the on relay 5|. Accordingly response of relay 80 providesfor continued energization of on relay 5i until it is deenergized byoperation of the limit switch it when the desired speed has beenattained.

The safe run switch 61 when closed provides for connection across linesL and L of the winding of relay 51 which upon responding opens itscontacts 51, thus disconnecting from line L the windings of the relayscontrolled by the various push button switches other than the off pushbutton switch.

Depression of the emergency push button 6 connects across line L thewinding of relay 25 of Fig. 2, thus providing for shut-down of the motoroperated generator set.

What I claim as new and desire to secure by Letters Patent is:

1. For printing presses and other machines, the combination with anhydraulic type drive comprising a generator and motor supplied thereby,of an electric drive comprising a motor capable of starting the drivenmachine, and control means for said drives insuring starting of thedriven machine always by said electric drive and afiording thereaftertransfer of drive to said hydraulic drive.

2. For printing presses and other machines, the combination with anhydraulic type drive comprising a generator and motor supplied thereby,of an electric drive comprising a motor capable of starting the drivenmachine, and control means for said drives insuring starting of thedriven machine always by said electric drive, af-

fording slow speed operation of the driven machine by said electricdrive and affording transfer of drive to said hydraulic drive for higherspeed operation of the driven machine.

3. For printing presses and other machines, the combination with anhydraulic drive comprising a generator and a motor supplied thereby, ofan electric drive comprising a motor capable of starting the drivenmachine, and control means for said drives insuring starting of thedriven machine always by said electric drive, affording slow speedoperation of the driven machine by said electric drive and affordingtransfer of drive to said hydraulic drive for higher speed operation ofthe driven machine, said control means including means affordingregulation at will and in small increments or decrements of the speed ofthe driven machine when operated by said hydraulic drive.

4. For printing presses and other machines, the combination with anhydraulic type drive comprising a generator and motor supplied thereby,of an electric drive comprising a motor capable of starting the drivenmachine, and control means for said drives insuring starting of thedriven machine always by said electric drive and affording thereaftertransfer of drive to said hydraulic drive and regulation of the speed ofsaid hydraulic drive, said control means affording a speed of saidhydraulic drive closely approximating that of said electric drive forsuch transfer.

5. For printing presses and other machines, the combination with anhydraulic type drive comprising a'generator and motor supplied thereby,of an electric drive comprising a motor capable of starting the drivenmachine, and control means for said drives insuring starting of thedriven machine always by said electric drive and affording thereaftertransfer of drive to said hydraulic drive, said control means includingmeans rendering such transfer of drive dependent upon establishment ofcertain operating conditions of said hydraulic drive.

6. For printing presses and other machines, the combination with anhydraulic type drive comprising a generator and motor supplied thereby,of an electric drive comprising a motor capable of starting the drivenmachine,. and control means for said drives insuring starting of thedriven machine always by said electric drive and affording thereaftertransfer of drive to said hydraulic drive, said control means includingmeans whereby if such transfer of drive is attempted when said hydraulicdrive is not in operation said electric drive will be maintainedeffective until said hydraulic drive is started or until stopping ofsaid electric drive is directed.

7. For printing presses and other machines, the combination with anelectric drive comprising a motor capable of starting the driven machineand operating it at slow speed, of an hydraulic type drive comprising agenerator and a motor supplied thereby capable of operating the drivenmachine at a speed approximating the aforementioned slow speed and athigher speeds, and control means to start the first mentioned motor andthereafter start the second mentioned motor for transfer of drive fromthe electric drive to the hydraulic drive when the two drives havesubstantially like speeds, said control means after such transferaffording regulation of the speed of said hydraulic drive in smallincrements and decrements.

8. For printing presses and other machines, the combination with anelectric drive comprising a motor capable of starting the driven machineand operating it at slow speed, of an hydraulic type drive comprising agenerator and a motor supplied thereby capable of operating the drivenmachine at a speed approximating the aforementioned slow speed and athigher speeds, and control means to start the first mentioned motor andthereafter start the second mentioned motor for transfer of drive fromthe electric drive to the hydraulic drive when the two drives havesubstantially like speeds, said control means after such transferaffording regulation of the speed of said hydraulic drive in smallincrements and decrements and said control means affording disconnectionfrom circuit of said electric drive after transfer to the hydraulicdrive.

9. For printing presses and other machines, the combination with anelectric drive comprising a motor capable of starting the driven machineand of operating it at slow speed and an over-running clutch throughwhich said motor drives, of an hydraulic type drive comprisingagenerator and a motor supplied thereby capable of operating the drivenmachine at a speed approximating the aforementioned slow speed and athigher speeds,

and control means to start the first mentioned motor and thereafterstart the second mentioned motor for transfer of drive from saidelectric drive to said hydraulic drive at a speed of the latter onlyslightly above that of the former, said control means following suchtransfer aflordlng regulation of the speed of said hydrauliis drive insmall increments and decrements.

10. For printing presses and other machines, the combination with anelectric drive comprising a motor capable of starting the driven machineand of operating it at slow speed and an over-running clutch throughwhich said motor drives, of an hydraulic type drive comprising agenerator and a motor supplied thereby capable of operating the drivenmachine at a speed approximating the aforementioned slow speed and athigher speeds, and control means to start the first mentioned motor andthereafter start the second mentioned motor for transfer of drive fromsaid electric drive to said hydraulic drive at a speed of the latteronly slightly above that of the former, said control means followingsuch transfer affording regulation of the speed of said hydraulic drivein small increments and decrements, and said control means insuring useof said electric drive in starting the driven machine for protection ofsaid hydraulic drive against overloads incident to starting.

11. For printing presses and other machines, the combination with anelectric drive comprising a motor capable of starting the driven machineand operating it at slow speed, of an hydraulic type drive comprising 'agenerator and a motor supplied thereby capable of operating said machineat a speed approximating the aforementioned slow speed and at higherspeeds, and control means for said drives to start the sameprogressively for starting of the driven machine by said electric driveand for continued operation by said hydraulic drive or optionally tostart only said electric drive for operation of the driven machine atslow speed only, said control means including means to guard against useof said hydraulic drive for starting.

12. For printing presses and other machines, the combination with anelectric drive comprising a motor capable of starting the driven machineand operating it at slow speed, of an hydraulic type drive comprising agenerator and a motor supplied thereby capable of operating said machineat a speed approximating the aforementioned slow speed and at higherspeeds, and control means for said drives to start the sameprogressively for starting of the driven machine by the electric driveand for continued operation by the hydraulic drive or optionally tostart only the electric drive for operation of the driven machine atslow speed only, said control means including means to guard against useof the hydraulic drive for starting and preventing starting of thehydraulic drive except when the electric drive is operating.

13. For printing presses and other machines,

an electric drive comprising a motor capable of,

starting the driven machine and operating it at slow speed and anover-running clutch through which said drive operates the drivenmachine, of an hydraulic type drive comprising a generator and a motorsupplied thereby capable of operating said machine at a speed onlyslightly above the aforementioned slow speed and at higher speeds, andcontrol means for said drives to start said electric drive alone or tostart b'oth drives, said control means rendering starting of saidhydraulic drive dependent upon prior starting and continued operation ofsaid electric drive.

14. For printing presses and other machines. an electric drivecomprising a motor capable of starting the driven machine and operatingit at slow speed and an over-running clutch through which said driveoperates the driven machine, of an hydraulic type drive comprising agenerator and a motor supplied thereby capable of operating said machineat a speed only slightly above the aforementioned slow speed and athigher speds, and control means for said drives to start said electricdrive alone or to start both drives,.

said control means rendering starting of said hydraulic drive dependentupon prior starting and continued operation of said electric drive andstopping said electric drive automatically after transfer from saidelectric drive to said hydraulic drive.

15. For printing presses and other machines, the combination with anelectric motor drive for starting and for slow speed operation of thedriven machine, of an hydraulic type motor drive for substantially likeslow speed and also higher speed operation of the driven machine andcontrol means for said drives to effect operation of said electric drivealone or operation of said hydraulic drive alone, said control meansincluding means insuring against starting of said hydraulic drive exceptwhen said electric drive is operating and said control means having acycle of operation for safety purposes and including means necessitatingits operation through such cycle for restarting whenever the drivenmachine is stopped following operation by either of said drives.

16. For printing presses and other machines, the combination with anelectric motor drive for starting and for slow speed operation of thedriven machine, of an hydraulic type motor drive for substantially likeslow speed and also higher speed operation of the driven machine andcontrol means for said drives affording inching or continuous operationof the driven machine by said electric drive alone or continuousoperation by said hydraulic drive alone, said control means includingmeans insuring against starting of said hydraulic drive except when saidelectric drive is operating and said control means having a cycle ofoperation for safety purposes and including means necessitating itsoperation through such cycle for restarting after each inching operationand after continuous operation of the driven machine by either of saiddrives.

17. For printing presses andother machines, the combination with anelectric motor drive for starting the driven machine and operating it atslow speed, of an hydraulic type drive comprising a power drivengenerator and a motor supplied thereby for operating the driven machinethrough an increased speed range, and control means for said drivesincluding means to render the motor of said hydraulic drive idle whileits generator operates and means to start said electric drive andthereafter start said hydraulic drive but only if operation of saidelectric drive is continued through the starting period of saidhydraulic drive.

18. For printing presses and other machines, the combination with anelectric motor drive for starting the driven machine and operating it atslow speed, of an hydraulic type drive comprising a power drivengenerator and a motor supplied thereby for operating the driven machinethrough an'increased speed range, and control means for said. drivesincluding means to render the motor of said hydraulic drive idle whileits generator operates and to render starting of said hydraulic drivedependent upon prior starting or said electric drive and operationthereof at the time starting 01' said hydraulic drive is directed andsaid control means also including means tending to continue operation ofsaid electric drive if the generator of said hydraulic drive is not inoperation when starting of said motor to be supplied thereby isdirected.

19. For printing presses and other machines, the combination with anelectric motor drive for starting the driven machine and operating it atslow speed, of an hydraulic type drive comprising a power drivengenerator and a motor supplied thereby for operating the driven machinethrough an increased speed range, and control means for said drivesincluding means to render the motor of said hydraulic drive idle whileits generator operates, and means to start said electric drive andthereafter start and accelerate said hydraulic drive and means effectiveto restrict accelerating operation of the last mentioned means in theevent starting of said hydraulic drive is directed while its generatoris not in operation.

20. For printing presses and other machines, the combination with anelectric motor drive for starting the driven machine and operating it atslow speed, of an hydraulic type drive comprising a power drivengenerator and a motor supplied thereby for operating the driven machinethrough an increased speed range, and control means for said drivesincluding means to render the motor 01' said hydraulic drive idle whileits generator operates, means to start said electric drive andthereafter start and accelerate said hydraulic drive, the last mentionedmeans having a motor driven device to effect a gradual increase in speedof said hydraulic drive, and means arrestingthe operation of said motordriven device when starting and acceleration of said hydraulic drive isdirected at a time that its generator is not in operation.

ERIC H. LAABS.

